Natural cytotoxicity and serum blocking in malignant cervical neoplasia.

Peripheral blood lymphocytes from 100 patients with various stages and histological types of squamous cell carcinoma of the uterine cervix were assayed for natural killer (NK) cell activity against K562 cells using the single cell cytotoxicity assay in agarose. The effect of autologous serum on NK cell activity and a quantitation of soluble antigen-antibody complexes was also carried out. The cancer patients showed reduced NK activity compared with normal controls, the reduction increasing with tumor load. Another observation was that patients with poorly differentiated tumours showed lower levels of NK activity. Addition of autologous serum resulted in further depression of NK activity in all groups of patients. An increase in circulating immune complexes was also evident in all groups of patients. Here again increase in tumor load and poorly differentiated tumors showed the highest levels. The results point toward a possible disturbance in NK cell activity that could be further depressed by autologous serum factors.